In semiconductor manufacturing, dry etch chemistries used for etching layers comprising silicon (such as a single crystal silicon, polysilicon, silicon dioxide, and silicon nitride) typically employ halogenated hydrocarbons (also known as halocarbons) as source gases. Common gases used to etch such silicon layers include CF.sub.4, C.sub.2 F.sub.6, or CHF.sub.3. These halocarbons are usually accompanied by oxygen or oxygen containing gases to achieve the appropriate chemical reactions to etch the silicon layer.
A concern in using halogenated hydrocarbons is that these gases have been implicated as a potential cause of global warming. During the dry etch process, a plasma generated within the etcher destroys or breaks down only a small fraction of the hydrocarbon source gases, leaving the rest to be vented into the earth's atmosphere.
Due to a growing concern for the environment and the potential problems of continued use of hydrocarbon source gases in semiconductor manufacturing, these gases may become scarce, more expensive, and/or heavily regulated by governmental agencies in an effort to discourage use. Therefore, semiconductor manufacturers would like to take the initiative to find alternative etch processes free from these environmental concerns.
One proposed solution to the problem halogenated hydrocarbon gases pose is the use of a post-etch exhaust gas treatment. In essence, such a treatment would be used to destroy any remaining halocarbon gases following the dry etch operation. There are various ways to destroy the dangerous gases, including hydrogen burn-off and molten elemental sodium treatment. In general, however, these abatement techniques are inefficient and expensive. Moreover, no catalytic destruct system yet exists.
Another proposed solution is the use of NF.sub.3 as a source gas. NF.sub.3 is a non-halocarbon gas which seems to adequately etch layers comprising silicon. Unfortunately, NF.sub.3 gas also attacks most dry etch reactor vessels, resulting in corrosion of the vessel and contamination of the semiconductor devices being etched. Moreover, NF.sub.3 gas is considerably more dangerous to handle than other gases used in semiconductor manufacturing.